1. Field of the Invention
The present invention relates to an injection quantity increasing mechanism for a governor in a fuel injection pump which is actuated at engine starting to make it easy to start an engine at extremely low temperatures.
2. Description of the Related Art
There have heretofore been proposed various governors mounted on a fuel injection pump of a diesel engine and adapted to increase and decrease the fuel injection quantity, thereby adjusting the output. For example, Japanese Utility Model Public Disclosure No. SHO 51-139818 discloses a governor adapted to be mounted on a straight type fuel injection pump. This prior art governor is of a so-called mechanical type and can adjust the injection quantity by transmitting a lift displacement of a weight provided on a cam shaft of an injection pump under centrifugal force to one end of a floating lever via a tension lever and a guide lever and by further transmitting the lift displacement to a control rack coupled to the other end of the floating lever. With the prior art governor, the control rack can be displaced to a position over its full load position by setting a control lever at a full-speed position, moving the control rack in a direction which increases the injection quantity through the floating lever and causing one end of a sensor lever having the other end thereof connected to the control rack to engage in a notch portion formed in a torque cam. Thus, the injection quantity can be increased at engine starting.
However, with the prior art governor having such an injection quantity increasing mechanism actuated at engine starting, when a diesel engine or an injection pump is driven in a cold region, the viscosity of lubricating oil introduced into the governor is increased to prevent the aforementioned mechanism from being smoothly operated. For this reason, the desirability of improving the mechanism has found widespread acceptance. Such improvements are disclosed in Japanese Utility Model Public Disclosures No. SHO 60-192239, No. SHO 61-29032 and No. SHO 61-55138, for example. In these improvements, a torque cam is forcibly driven by an actuator using a solenoid or a shape memory effect alloy, or a weight is forcibly lifted by displacing a shifter pivotally attached to the lower end of a tension lever in a direction of the side of the weight, thereby facilitating the movement of the tension lever and a guide lever. However, these improvements require use of an actuator or another drive means for operating the torque cam or the shifter, which constitutes an additional part. Furthermore, the work of mounting the additional part is cumbersome. Furthermore, since this kind of mechanism has strict limitations on part dimensions, and it is very difficult to obtain mounting space for the aforementioned additional part from a standpoint of design considerations.